This is something that I've thought about off-and-on, and while reading a Hot Question on English Language Learners SE recently I followed a link to a meta Q&A there called Not so fast! (When should I accept my answer?).
I had been thinking, and this Q&A presents it really well, that it seems like many Q&As on GIS SE that have answers accepted not long after the question is asked only have one answer, whereas many that don't have accepted answers (or answers are accepted later) may have 2 or 3 answers. I don't have any numbers to back this up though, this is just an unscientific observation.
Do Questions with Accepted answers put people off adding their own (potentially better) answers? Do we accept too early and therefore lower the chance of getting an amazing answer while settling for one that may or may not actually answer the question well?
The ELL SE Q&A links to a Meta SE Q&A How does accepting an answer work? which talks about when we should accept answers
Accepting an answer is important as it both rewards posters for solving your problem and informs others that your issue is resolved.
However, that post also says:
You might wait 24 to 48 hours to give other people a chance to give you a better answer. A question with an accepted answer isn't as likely to receive further attention as one without an accepted answer.
Are we discouraging additional answers to questions by accepting answers too quickly?
Of course the flip-side to this is that if we recommend people hold off a bit before accepting answers, they may forget and never accept any at all...
I did a bit of a query on Stack Exchange Data Explorer to find the average number of answers if a) answer accepted within a day of the question being asked, vs b) answer accepted more than a day after the question asked.
1.43- Average number of answers where an answer is accepted within a day
1.66- Average number of answers where the answer isn't accepted for more than a day
The difference doesn't sound huge, but if I make the number of days higher the value grows. In other words, the longer it takes for an answer to be accepted, the more answers that are added to the question. Hopefully there's nothing wrong with my SQL or my maths here! Data Explorer doesn't actually expose the time an answer is accepted, only the date, so I can't refine this much better.